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Fwd: CC No turning back on Arctic warming

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  • Pat Neuman
    ... wrote: No turning back on Arctic warming Scientists fear effects on polar lakes irreversible Climate changes traced back to 1850s, study finds PETER
    Message 1 of 1 , Mar 1, 2005
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      --- In fuelcell-energy@yahoogroups.com, "janson2997" <janson1997@y...>
      wrote:

      No turning back on Arctic warming
      Scientists fear effects on polar lakes irreversible

      Climate changes traced back to 1850s, study finds

      PETER CALAMAI
      SCIENCE REPORTER

      OTTAWA-A circumpolar investigation led by Canadian scientists has
      discovered clear signs of climate change in scores of Arctic lakes
      dating back to the mid-19th century, when the Industrial Revolution
      kicked off widespread burning of fossil fuels.

      Warmer temperatures have pushed some plant and animal life in the
      lakes over an ecological threshold that won't be reversed for
      generations, if ever, the scientists conclude in a study released
      yesterday.

      "We're seeing big changes occurring in lakes and ponds all around the
      Arctic. It's not just algae but also invertebrates like water fleas
      higher up the food chain," said University of Toronto professor
      Marianne Douglas, a polar lake expert and one of the lead researchers.

      The study also found the ecological changes became greater the farther
      north the lakes were located, just as average temperatures have risen
      more in the High Arctic than farther south at the Arctic Circle.

      The lakes don't look much different, lacking anything as dramatic as
      the green scum that coated parts of Lake Erie when over-fertilized
      with nutrients in the 1970s. One scientist compared the change to the
      ecosystems being shifted into overdrive.

      Douglas said mud cores from 46 Arctic lakes in Canada and three other
      countries showed clear evidence of a longer growing season beginning
      as far back as the 1850s, well before thinning pack ice and starving
      polar bears currently being linked to global warming. Russia, Norway
      and Finland provided the other research sites.

      The long-term evidence comes from the distinctive glassy casings of
      single-celled algae called diatoms that rain to the lake bottom as the
      algae die. Experts can read the past climate from the layers of
      sediment since some diatoms do better under ice and others in clear
      water.

      Douglas said the sediment cores suggest that many of the lakes were
      now ice-free a month longer than in the mid-1800s, doubling the
      growing season for some diatoms. This has produced a surge in
      Cyclotella, a diatom that thrives only under open water conditions.

      Lead researcher John Smol of Queen's University said the study should
      put the final nail in the coffin of arguments that climate change is
      not happening.

      "This is a completely new independent set of data and wasn't included
      in earlier studies the skeptics spend so much time attacking," said
      Smol, who pioneered the study of Arctic lake sediments in Canada.

      This view was echoed by John Hobbie, a leading American expert in
      Arctic lakes who was not one of the 26 researchers involved in the
      unprecedented circumpolar investigation.

      "We had thousands of years with no changes in the algae species. Now
      they've shown that changes occur in places where warming is going on
      and, more importantly, don't occur where there is no warming," said
      Hobbie, co-director of the renowned Marine Biological Laboratory at
      Woods Hole in Maine.

      Smol also said ecosystems in the Arctic lakes would need several
      generations to switch back to their previous condition and that could
      happen only if the world actually reduced atmospheric levels of
      greenhouse gases like carbon dioxide.

      The study, published by the U.S. National Academy of Sciences, is
      something of a vindication for Smol and the UofT's Douglas.

      In 1994, they ran into widespread doubts among colleagues after
      publishing similar diatom results from just three lakes on Ellesmere
      Island in Canada's Arctic archipelago.

      "Some thought the changes couldn't have started as early as the
      mid-1800s and that there must be some other explanation," said Smol,
      the 2004 winner of Canada's premier science award, the Herzberg Gold
      Medal.

      One of those earlier skeptics, Alex Wolfe, is now a co-author of the
      new paper and a paleoecologist at the University of Alberta. He became
      convinced after finding the same evidence in his own lake sediment
      cores.

      "We have low-productivity, sensitive ecosystems that are essentially
      cast into overdrive," Wolfe said, speaking from the remote Norwegian
      island of Svalbard, where he is doing research.

      "I would stake my reputation against the lakes reverting back to what
      they looked like 1,000 years ago ... Ever," Wolfe added.

      Additional articles by Peter Calamai

      http://www.thestar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_PrintFriendly&c=Article&cid=1109631011232&call_pageid=970599119419

      j2997
      --- End forwarded message ---
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